Extensive works on a pair of century-old foot tunnels beneath the Thames that would include replacing lift attendants with CCTV cameras are in crisis.

The Government-funded facelift of the Greenwich and Woolwich tunnels was meant to be complete by summer last year. But work is at a standstill with no lifts at Woolwich and unreliable ones at Greenwich.

The works have exceeded the £11.4 million grant, but Greenwich council refuses to say by how much. Bosses want to sue the contractors to recoup some of the costs.

At a cabinet meeting this week, council leader Chris Roberts did not reveal who would complete the work or how much it would cost.

The tunnels are used by two million people annually and are popular with cyclists.

The works by a subsidiary of one of Britain’s biggest construction firms, Balfour Beatty, began in early 2010. When they were still incomplete last Christmas, Labour-run Greenwich terminated the contract.

Greenwich forecasts a further four months will be needed to complete the project but will not say when work will recommence.

Dean & Dyball Civil Engineering won the tender for the work with a bid of just over £9 million. It left Greenwich nearly £2.5 million from the grant but it was not enough.

Liberal Democrat London Assembly member Caroline Pidgeon said: “It is time Greenwich council admitted exactly why the budget has gone through the roof and the tunnels are still in such an appalling state.”